Phenylephrine and pharmaceutically acceptable salts thereof are recognized by those skilled in the art as safe and effective nasal decongestants for humans when administered at frequent intervals. Commercially-available formulations include nasal jelly, nasal drops, and nasal spray (i.e. Alconefrin® Nasal Drops or Neo-Synephrine® Nasal Jelly) as well as immediate release oral tablets or gelatin capsules (i.e. Sudafed PE™ or DayQuil® LiquiCaps). Due to a short half-life of the active phenylephrine species in plasma in vivo, phenylephrine and pharmaceutically acceptable salts thereof as currently formulated are commonly administered every four hours for the relief of nasal congestion.
Therefore there is an unmet need for less frequent delivery of phenylephrine for patient convenience and for sustained availability of the therapeutically active phenylephrine within a subject in need of such administration.
Less frequent administration results in improved patient compliance with appropriate dosing regimens. In addition, constant therapeutic plasma levels of active components can be more effective and even efficacious compared to the fluctuations seen when multiple doses of a conventional immediate release formulation are given, providing sustained effective levels and decreasing the severity and frequency of side effects from high peak plasma levels. Thus, formulations of phenylephrine that can be administered less frequently, for example, once every 8, 12, 16, 20, or 24 hours, are needed.